1. Field of the Invention
The present invention is generally directed to an apparatus and a method for providing a mechanical interlock of a lever operated receptacle with a shaft operated switch. More specifically, a mechanically interlocked ground switch, main power switch, receptacle, and receptacle handle lever prevents energizing the receptacle or disconnecting the ground switch without the plug being inserted and locked into the receptacle. Further, the unlocking or disengaging of the plug while the switch is on and ungrounded is mechanically and reliably prevented. In other words the power switch cannot be turned on without a properly inserted plug and the plug cannot then be removed with the switch remaining in the on position.
2. Prior Art
Interlock systems of other lever operated receptacles in use in modern electrical systems may employ an electrically interlocked system using logic to disallow potentially dangerous or undesirable conditions. However, if the electrical system fails for any reason, the electrical interlock system would also fail—potentially resulting in casualty or damage to powered systems.
Another strategy is to use a key interlock system where a key is used to restrict access to and limit potential states of the system. However this faces the drawbacks of heightened expense, complicated key logistics, key access accounting, access control, and secure storage balanced with accessibility. If a key should be lost, the system is rendered inoperative until a replacement key can be identified and procured. In an emergency situation, this can result in catastrophic losses and delay costs brought about by lost productivity, late deliveries, missed deadlines, locksmiths, as well as key administration costs.
More importantly, the system is able to be undermined through the use of duplicate keys or neglecting to re-lock the systems appropriately. Such a system is entirely dependent on users remembering and choosing to relock the system each and every time.
Another conventional means to ensure proper operation of an electrical receptacle and switch is operator training. Operators are simply trained to perform operations in a specified sequence so as to reduce harm to components and personnel. However, this is difficult to enforce and exposes personnel and hardware to great risks should the procedures not be followed correctly. Again, such a system is entirely dependent upon voluntary compliance each and every time by users.
Thus, one problem associated with conventional power switches and receptacles is the exposure of technicians or ordinary users to potentially dangerous and even life threatening situations where interlock systems are susceptible to failure and lack assured enforcement of safety procedures. Such systems are easily undermined, omitted, or broken.
Yet another problem associated with conventional power switches is the ease with which one can overcome the previous protection schemes either maliciously, through laziness, or improper user/technician education.